<script setup lang="ts">
import { provide } from 'vue'
import A from './A.vue'
import { titleKey } from './symbolkey'
// 把key传入第一个参数的位置，限制第二个参数必须是string类型
provide(titleKey,'this is a title')
</script>

<template>
  <div>
    this is app
    <A/>
  </div>
</template>

